1. Vehicle Informatics (Vehicle System Informatics)
Lecture
Part 05
(MOST)
Dr. Tamás Szakács:
Ákos Jányoki:

2. MOST (Media Oriented Systems Transport)
A high-speed (Up to 150Mb/s) multimedia network technology optimized by the automotive industry. Can be used for applications inside or outside the car.
JInfo_EA_kommunikacio-BME.pdf

3. MOST (Media Oriented Systems Transport)
MOST technology is used in almost every car brand worldwide, including Audi, BMW, General Motors, Hyundai, Jaguar, Lancia, Land Rover, Mercedes-Benz, Porsche, Toyota, Volkswagen, SAAB, SKODA, SEAT and Volvo. SMSC and MOST are registered trademarks of Standard Microsystems Corporation (“SMSC”), now owned by Microchip Technology.
JInfo_EA_kommunikacio-BME.pdf

4. MOST MOST is a synchronous network.
A timing master supplies the clock with a synchronous and continuous data signal
All other devices synchronize their operation to this base signal.
This technology eliminates the need for buffering and sample rate conversion
Very simple and inexpensive devices can be connected
The hardware of the network interface itself is lean and cost effective.
The technology is similar to what the public switched telephone network uses.
mostcooperation.com

5. MOST Within the synchronous base data signal,
multiple streaming data channels
one control channel are transported.
The control channel is used to set up what streaming data channels the sender and receiver are to use. Once the connection is established, data can flow continuously and no further addressing or processing of packet label information is required.
The bandwidth of the streaming data channels is always available and reserved for the dedicated stream so there are no interruptions, collisions, or slow-downs in the transport of the data stream. This is the optimum mechanism for delivering streaming data (information that flows continuously) like audio and video. MOST has been designed for high quality of service and cost effective transport of audio and video.
mostcooperation.com

6. MOST
Sending asynchronous, packet based data in addition to the control channel and the streaming data
Runs on top of the permanent synchronous data signal
Completely separate from the control channel and the streaming data channels so that none of them interfere with each other
for computer based data, such as Internet traffic or information from a navigation system, is typically sent in short (asynchronous) bursts as packets and is often going to many different places
mostcooperation.com

7. MOST Frame
The structure of the MOST frame

8. MOST Frame The structure of the MOST frame
The first part is the preamble, which is 4 bits long and means the start of the frame. Each frame in a block has his own preamble. Its task is to synchronize the clock between the Slaves and the Master.
Second part is the boundary descriptor / delimiter which is 4 bits long as well, and separates the preamble from the data field.Specifies how are the available bytes of the data field divided for synchronous and asynchronous part.

9. MOST Frame Data Field The structure of the MOST frame
The value of the the boundary descriptor is between 6 and 15 (decimal), and the expected sync data is obtained by being multiplied by 4. The result will show the number of the synchronous bytes from the total possible 60 bytes.
JInfo_EA_kommunikacio-BME.pdf

10. MOST Frame Data Field
Asynchronous data (eg navigation data, images, messages, vectors, etc.) are transmitted when a control unit receives a frame whose recipient is the same as the one you want to send asynchronous data, and there is still room left in the frame (Quadlet) in the data field. That is, asynchronous data is irregular at intervals and also will be transmitted in "Quadlets" (4 bytes)
JInfo_EA_kommunikacio-BME.pdf

11. MOST Check Byte and Check Frame
Check byte (control bytes):
contain the sender's and recipient's ID and the commands, control signals for the destination controller, such as input switching, or
any request to change any setting (eg volume change, EQ, etc.)
Check frame:
16 Check byte pairs (16 frames, 32 bytes)
JInfo_EA_kommunikacio-BME.pdf

12. MOST Summarized
MOST is a multiplex network that has different channels with their own mechanisms to transport all the various signals and data streams that occur in multimedia and infotainment systems.
They all run on top of a synchronous base data stream which guarantees high quality of service for the audio and video signals where disturbances are not acceptable.
mostcooperation.com

13. Key Features MOST Ease of use Simple connectors
No hum loops, no radiation
Plug-n-Play; self identifying devices with auto initialization
Dynamically attachable and re-configurable devices
Virtual network management including channel allocation, system monitoring addressing and power management
mostcooperation.com

14. Key Features MOST Wide application range
applications with varied bandwidth requirements
high degree of data integrity with low jitter
support of asynchronous and synchronous data transfer
support of multiple masters
supports up to 64 devices
simultaneous transmission of multiple data streams such as control, packet and real-time information
devices can be constructed out of multiple functions
low overhead due to embedded network management
mostcooperation.com

15. Key Features MOST Synchronous bandwidth Asynchronous bandwidth
synchronous channels provide guaranteed bandwidth with no buffering required
Asynchronous bandwidth
variable asynchronous bandwidth with additional dedicated real-time control channels
mostcooperation.com

16. Key Features MOST Flexibility
wide range of real-time channel sizes and packet sizes
remote operation and flow control
variable asynchronous bandwidth with additional dedicated real-time control channels
protocol independent
mostcooperation.com

17. Key Features MOST Synergy with Consumer and PC Industries
operates with or without PC
consistent with PC streaming
Low Implementation Cost
low cost channel to distribute control information without extra wiring
zero data overhead to move synchronous data after a connection is established
synchronous channels eliminate the need for buffering and sample rate conversion
suitable for embedding in consumer devices and peripherals
cost-effective electrical and optical solutions
inexpensive silicon from many suppliers
mostcooperation.com

18. Bus Systems Overview

19. MOST Application Overview

20. MOST Bandwidth Overview

21. OSI / ISO MOST
mostcooperation.com

22. MOST Topologies
mostcooperation.com

23. MOST Topologies Point to point Ring Ring incorporating splitters
Star of rings
mostcooperation.com

24. MOST Topologies
Star of rings
mostcooperation.com

25. MOST Topologies
Ring structure
mostcooperation.com

26. MOST Cabling
Connectors
mostcooperation.com

27. MOST Cabling
Construction of fiber optic cable
mostcooperation.com